Cyclic freezing and thawing of soils affect the structure and might, under certain conditions, cause stones and particles to move and relocate. The movement of stones will influence the soil structure and create weak and loose parts with increased permeability. This phenomenon has been known for a long time, but the knowledge regarding the magnitude of stone heave and soil conditions necessary for heave to take place has been lacking. Therefore, laboratory tests were carried out. Fine-grained till (moraine) was compacted to different void ratios and then saturated in a rigid wall permeameter which was exposed to one-dimensional freezing and thawing in a closed water system. The movements of an embedded stone were measured by an X-ray technique. Unfrozen samples, as well as samples frozen and thawed, were X-rayed and the stone movements were quantified after 1, 2, 4, and 10 cycles of freezing and thawing. The results show that stone movements (vertical and horizontal) take place due to freeze/thaw. The void ratio (the ratio of the volume of void space to the volume of solid substance in the sample) was found to be a key parameter for whether upward or downward stone movements took place. The downward movement occurred when the soil had a high void ratio, and the upward when the void ratio was small. In the loose soil, the stone first moved downwards and then, when the soil became denser due to freeze/thaw, it changed direction and heaved. In the loose soil, significant movements in the horizontal direction as well as rotation of the stone were also found.

A fine-grained nonplastic till was compacted in the laboratory in three types of rigid wall permeameters, having a volume of 0.4, 1.5, and 25 dm3, respectively, and, was thereafter exposed to a maximum of 18 freezing and thawing cycles. The permeabilities in the vertical direction of saturated samples were measured in unfrozen soil as well as in thawed soil. The results show that the permeabilities changed after freezing and thawing. The magnitude of the changes in this study were in the range 0.02-10 times after freeze/thaw compared with the unfrozen soil. Soil exhibited volume changes subsequent to freeze/thaw. The volume typically decreased for an initially loose soil and increased for a dense soil. Independent of whether the initial soil structure was loose or dense, a constant `residual' void ratio, eres, was obtained after 1-3 cycles. For the soil investigated, the residual void ratio ranged from 0.31 to 0.40

Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured. Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured. Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured.

Frozen soils compaction are understood to give fills with low densities. Thus, relatively large deformations often occur when such fills melts. The most important factors influencing the obtained dry density, and consequently the thaw deformations, are compaction effort, temperature, water/ice content and soil type. A laboratory investigation was conducted in order to quantify the different factors influencing the obtained degree of compaction, as well as related thaw deformation. The results indicated that the water content of the soil is the most important factor for the obtained dry densities and for the thaw compressions

Density measurements, unconfined compression tests, creep tests, beam tests, and measurements of deformations were performed on snow and snow structures that formed the Icehotel during the winter 2000/2001. Results from the unconfined compression tests and creep tests showed that: At -5ºC unconfined compression strength was 0,598 MPa with a snow density of 532 kg/m3. Axial viscosity was 3,23·106 MPa-s and compactive viscosity was 5,24·106 MPa-s with a snow density of 524 kg/m3. At -10ºC unconfined compression strength was 0,681 MPa with a snow density of 558 kg/m3. Axial viscosity was 1,92·106 MPa-s and compactive viscosity was 1,38·106 MPa-s with a snow density of 518 kg/m3. At -11ºC unconfined compression strength was 0,879 MPa with a snow density of 550 kg/m3. Axial viscosity was 2,16·106 MPa-s and compactive viscosity was 2,79·106 MPa-s with a snow density of 470 kg/m3. Beam tests were performed on snow from a pile of artificially made snow. This type of snow was used to construct the arcs of the Icehotel. Results from the beam tests showed that the snow had a mean density of 510 kg/m3 and that Young's modulus E had a mean value of 335 MPa. At failure mean value of maximum tensile- and compression stress was 0,375 MPa and mean value of maximum shear stress was 0,039 MPa. During the winter 2000/2001 deformations of the church building were measured. Results show that the apex of the arcs actually rose 4 to 8 cm, though the shape of the arcs changed very little. Comparing results from this investigation with results from earlier investigations made on snow with similar densities showed that: Unconfined compression strength was 20 to 40 percent lower. Axial viscosity was similar in all but one test at -10/-11 ºC. Axial viscosity was in all tests higher at -5 ºC. Compactive viscosity was higher in all tests. Results from the beam tests regarding Young's modulus values and tensile strength showed similar results.

Sand compaction piles are used in practice for ground improvement of weak subsoil. These columnar inclusions improve the consolidation behaviour as well as reduce the compressibility of the soft ground. The current design procedure of these sand piles is based on simple empirical calculations, which does not fully take account of the sand pile behaviour. In order to gain a deeper understanding of the behaviour of sand compaction piles, physical and numerical investigations are being conducted. The basic system behaviour of soft soil and column is simulated physically by centrifuge modelling. Because the stress situation in the soil changes significantly due to installation, a sand compaction pile installation tool was developed and applied successfully in the first tests. This allowed the stress paths encountered by the soil during the construction process of a displacement sand pile to be modelled realistically. The results will be compared to real geometries and the behaviour is also studied numerically by means of finite element modelling. These findings provide the basis for further analysis of this geotechnical interaction problem extending the model by including geotextiles below embankments to be able to formulate some recommendations for the design procedure of sand compaction piles under embankments.

Stone columns are primarily used for the purpose of ground improvement in fine grained soils in order to reduce settlements and the risk of bearing failure. They are also designed to improve the drainage conditions in the ground and to accelerate the consolidation processes within the clay. However, smear and disturbing effects caused during the construction of stone columns result in degradation of consolidation performance in comparison with the theoretically ideal conditions. Model stone columns are constructed in-flight under 50 times gravity in centrifuge tests and the soil micro-structure in the vicinity of these columns is investigated by applying different methods, including environmental scanning electron microscopy and mercury intrusion porosimetry. The results these tests confirm that smear and disturbance occur owing to stone column installation and the region influenced can be divided into three sections: a penetration zone (1) where the sand particles are squeezed through the clay; a smear zone (2) where the soil particles have experienced a significant reorientation; and a densification zone (3) where the structure of the clay does not appear to change, but compaction of the clay is measurable. The extremes of the disturbed zone around model stone columns are determined to extend to about 2.5 times the column radius.

Deterministic methods have been used in geotechnical engineering for a long period, such as slope stability calculations. However, only applying deterministic methods is subjective and imperfect. There is a demand to develop a systematic methodology to link the assessed slope stability and field measurement data, which is also known as inverse analysis and forward calculation.

Based on the Nya Slussen project, this thesis includes the development of a methodology, deterministic calculation for 4 cross sections using finite element program Plaxis 2D and probabilistic calculation for one section. Deterministic analyses showed satisfying results for all the studied cross sections since their factors of safety exceeded the minimum requirement. In probabilistic design, three parameters were found to have the most uncertainties through sensitivity analysis (undrained shear strength of clay, Young’s modulus of clay and friction angle of fill). Inverse analysis was done by testing different values of them in Plaxis and to try to match the displacement components provided by field measurement. After finding the best optimization for all the parameters, forward calculation gave a final factor of safety. It is suggested that both of the methods should be utilized together for better assessment.

Vibratory rollers are commonly used for compaction of embankments and landfills. This task is time consuming and constitutes a significant part of most large construction and infrastructure projects. By improving the compaction efficiency, the construction industry would reduce costs and environmental impact.

This research project studies the influence of the vibration frequency of the drum, which is normally a fixed roller property, and whether resonance can be utilized to improve the compaction efficiency. The influence of frequency on roller compaction has not before been studied but the concept of resonance compaction has previously been applied successfully in deep compaction of fills and natural deposits.

In order to examine the influence of vibration frequency on the compaction of granular soil, small-scale compaction tests of sand were conducted under varying conditions with a vertically oscillating plate. Subsequently, full-scale tests were conducted using a vibratory soil compaction roller and a test bed of crushed gravel. The results showed that resonance can be utilized in soil compaction by vibratory rollers and plates and that the optimum compaction frequency from an energy perspective is at, or slightly above, the coupled compactor-soil resonant frequency. Since rollers operate far above resonance, the compaction frequency can be significantly reduced, resulting in a considerable reduction in fuel consumption, environmental impact and machine wear.

The thesis also presents an iterative equivalent-linear method to calculate the frequency response of a vibrating foundation, such as a compacting plate or the drum of a roller. The method seems promising for predicting the resonant frequency of the roller-soil system and can be used to determine the optimum compaction frequency without site- and roller-specific measurements.

Vibratory rollers are commonly used for compaction of embankments and landfills. In a majority of large construction projects, this activity constitutes a significant part of the project cost and causes considerable emissions. Thus, by improving the compaction efficiency, the construction industry would reduce costs and environmental impact. In recent years, rollers have been significantly improved in regard to engine efficiency, control systems, safety and driver comfort. However, very little progress has been made in compaction effectiveness. While the compaction procedure (e.g. layer thickness and number of passes) has been optimized over the years, the process in which the machine compacts the underlying soil is essentially identical to the situation in the 1970s.

This research project investigates the influence of one crucial parameter, namely vibration frequency of the drum, which normally is a fixed roller parameter. Frequency is essential in all dynamic systems but its influence on the compaction efficiency has not been studied since the early days of soil compaction. Since laboratory and field equipment, measurement systems and analysis techniques at the time were not as developed as they are today, no explicit conclusion was drawn. Frequencyvariable oscillators, digital sensors and computer‐based analysis now provide possibilities to accurately study this concept in detail.

In order to examine the influence of vibration frequency on the compaction of granular soil, small‐ scale tests were conducted under varying conditions. A vertically oscillating plate was placed on a sand bed contained in a test box. The experiments were carried out in laboratory conditions to maximize controllability. The first test setup utilized an electro‐dynamic oscillator where dynamic quantities, such as frequency and particle velocity amplitude, could be varied in real‐time. The second test setup included two counter‐rotating eccentric mass oscillators, where tests were conducted at discrete frequencies. This type of oscillator has a force amplitude that is governed by frequency.

The main objectives of the tests were to determine the optimal compaction frequency and whether resonance can be utilized to improve compaction efficiency. Results showed that resonance had a major influence in the electro‐dynamic oscillator tests, where the applied force amplitude is low, and the optimal compaction frequency is the resonant frequency under these circumstances. In the rotating mass oscillator tests, where a high force was applied to the plate, resonant amplification was present but not as pronounced. Since force increase with frequency, the optimal frequency to obtain the highest degree of compaction is very large. In a practical regard, however, frequency should be kept as low as possible to minimize machine wear and emissions while still achieving a sufficient compaction of the soil. Considering the practical issues, it is proposed that surface compactors should operate slightly above the resonant frequency. However, the applicability to vibratory rollers must be confirmed in full‐scale tests.

The thesis also presents an iterative method to calculate the frequency response of a vibrating plate, incorporating strain‐dependent soil properties. Calculated dynamic quantities are compared to measured values, confirming that the method accurately predicts the response.

Ground-borne vibration from railway traffic is an increasing problem in urbanized areas and measures are often needed to minimize its effects on the environment. An important question when dealing with railway problems is to identify the source(s) of vibration emitted along the railway track. Once this information is available, it is often possible to mitigate the problem by improving stiffness of the railway track and/or to upgrade worn-out or damaged rail sections and turnouts. This paper describes a method which makes it possible to determine the locations of track sections which are likely to emit strong ground vibration. A purpose-built track-bound vehicle which can be vibrated continuously at different frequencies can identify track sections having unfavorable dynamic foundation conditions. A theoretical concept is proposed to calculate the potential of energy emission from the vehicle moving along the track. Further, an innovative method is presented which makes it possible to determine the location of vibration sources by measurement of ground vibrations from existing railway traffic. This information can be used to determine the location of track sections where remedial measures are needed. Results are presented, illustrating application of the concepts, which can also be applied to other types of vibration problems.

Vibratory rollers generally operate at a fixed vibration frequency. It is hypothesized that the compaction of soil could be made more efficient if the frequency could be adapted to specific project conditions. In order to study the applicability to surface compaction, the frequency dependence of compacting dry sand with a vertically vibrating plate was investigated experimentally in 85 small-scale tests. Tests were performed in a test box simulating the free-field condition and with concrete underlying the sand bed. The results show that there is a distinct frequency dependence, implying a significantly improved compaction effect close to the compactor soil resonant frequency. It is suggested that particle velocity is the governing amplitude parameter for vibratory soil compaction, rather than displacement or acceleration. As the soil is compacted, it is also displaced, resulting in surface heave. A larger vibration amplitude implies greater displacement relative to the compacted volume. It was also observed that the compaction and strain-dependent reduction of soil stiffness are closely related.

A method for calculating the dynamic response of a vertically oscillating foundation on soil with strain-dependent properties is developed. Strain-dependent stiffness and damping are incorporated by an iterative procedure, presenting the response in frequency domain. The calculated dynamic displacement amplitudes are compared to small-scale tests using a vertically oscillating plate. The calculated dynamic quantities agree well with measured amplitudes over a wide frequency range.

The influence of vibration frequency was studied in 110 small-scale compaction tests conducted using a vertically oscillating plate. The underlying soil was dry sand, or sand close to the optimum water content. The results showed that there is a resonant amplification, providing a slightly higher degree of compaction. Frequency has a major influence on soil compaction. An iterative method for calculating the dynamic response of the plate, incorporating strain-dependent properties of the soil, is also presented. The calculated frequency response agrees fairly well with measured quantities.

Soil heave due to pile driving in clay is discussed and, in particular, its influence on adjacent piles. Finite element studies and results of model tests are presented and compared with field measurements. It is demonstrated that in the vicinity of the driven pile, the soil is displaced mainly in the lateral direction, similar to soil subjected to passive earth pressure. General rules of estimating soil heave inside and outside a pile group are examined. A method is proposed for estimating soil heave when driving a group of piles. Practical application of predicting soil heave is illustrated by an example.

Prediction and monitoring of vibrations from rock blasting is of practical importance. Damage to rock tunnels caused by blasting is fundamentally different to that of conventional buildings. Different damage mechanisms are discussed as well as methods to monitor the development of cracks by analysis of frequency content. For the assessment of the damage potential it is essential to understand wave propagation in rock and the dynamic response of cavities to vibration excitation. Vibration frequency and wavelength in relation to the size of the cavity are important parameters. Vibration amplification of a circular tunnel to a plane wave is analyzed and guidelines given for practical design applications. Filtering the vibration signal, which is often required in national standards, car. give misleading results for tunnels in rock.

Full-scale tests were conducted to study the influence of the operating frequency of a vibratory roller on the compaction of crushed gravel in a controlled environment. Tests were performed at both fixed and variable frequencies. The average densification of the soil was represented by settlement of the ground surface, and depth-dependent density variation before and after compaction was determined by horizontal nuclear density gauge measurements. The resonant frequency was approximately 17 Hz and frequencies in the range 15–35 Hz were tested. The optimum compaction frequency was determined to be around 18 Hz; that is, slightly above resonance, as compared with the standard operating frequency of the roller, 31 Hz. Lower compaction frequency significantly reduces the required engine power and thus fuel consumption and environmental impact, while increasing the lifespan of the roller. Furthermore, the soil closest to the ground surface is loosened at high frequency. This can be avoided with a lower compaction frequency and the need for subsequent static passes can thereby possibly be eliminated.

In order to perform a complete risk analysis of a dam facility, it is necessary to have information about the probability and consequences of failure. To analyze the probability of failure of a concrete dam, all components and all failure modes must be accounted for. This paper presents a methodology for the calculation of the failure probability of a concrete dam with respect to foundation stability where the dam is considered as a system. The system is divided into different levels, where the top event on the "structure level" is failure of the dam. The next level is "monolith level", where each monolith can be considered as an element in a series system of the concrete dam. Below the monolith level is the "failure location level" which describes where the failure occurs, in the concrete-rock contact, in the rock mass or in the concrete. Since it is the weakest of these failure locations that will govern where the failure occurs, each failure location can be seen as elements in a series system. Beneath this level is the "failure mode level" where failure modes such as sliding and rotation also constitute elements in a series system. The "Basic failure modes" are the foundation level in the system. In some situations, the reliability of all failure modes as well as the correlation between failure modes is of importance for the overall reliability. In other situations only the reliability of a dominant failure mode is of importance. A discussion regarding this is given.

The main objectives if the research project have been to create an experimental basis for a more general theoretical modelling of Swedish clays and to improve the knowledge of the mechanical behaviour of natural soft clays. Another objective has been to investigate the effects of end restraint on the mechanical behaviour obtained in triaxial tests, by means of numerical simulations. Extensive experimental studies were performed by triaxial tests on a natural soft clay from the city of Norrköping. The results are discussed in detail from a quantitative and qualitative point of view and the effects of the in situ structure of the clay on the mechanical behaviour focused. Undrained and drained shear conditions are investigated. Obtained deformation modes in triaxial tests ar classified and analysed. Soil parameters for constitutive models are evaluated and discussed and requirements formulated for a constitutive model supposed to describe the behaviour of the clay.

A recently started research project concerning strength and deformation properties of Swedish fine-grained sulphide soils is presented. The scope of study is outlined. The overall purpose of the project is to find suitable testing methods in field and laboratory to determine reliably the mechanical properties of fine-grained sulphide soils. In this paper, some test results of undrained shear strength of sulphide soils, determined with different test methods at two test sites, is presented. The results confirm that there is a need for calibration of the different evaluation methods in order to obtain relevant values in fine-grained sulphide soils.

Sulphide soil is the dominating fine-grained soil type along the east coast of the northern part of Sweden. A sulphide soil typically consists of clay and silt fractions with various and smaller content of sand. Sulphide soil may contain high amounts of iron mono sulphides (FeS) and organic content up to about 10%. A fine-grained sulphide soil normally shows low strength and high compressibility. Previous research concerning strength and deformation properties of Swedish fine-grained soils has very little included sulphide soil. It has been found that field and laboratory methods used to determine properties of other fine-grained soils, are often not suitable for sulphide soil.In this paper results from field and laboratory testing of fine-grained sulphide soil are presented and discussed. In the field, field vane tests, CPT-tests, dilatometer tests, seismic CPT-tests and undisturbed sampling are conducted. In the laboratory, triaxial tests, direct shear tests, oedometer tests, CRS-oedometer tests, routine tests of basic geotechnical properties and tests to determine chemical properties are done. In the laboratory, testing is carried out in room temperature as well as for in situ soil temperature for samples handled either at normal air conditions or at air free conditions.The main purpose of the research project is to find suitable testing methods in field and laboratory to determine mechanical properties of fine-grained sulphide soils. This includes how the results should be interpreted and evaluated and how samples should be sampled, transported, stored, handled and tested. In the paper the first part of the project is reported, including comparisons between properties and parameters determined in field and in laboratory. Effects on mechanical properties of testin g in room temperature versus in situ soil temperature and effects of handling the sample at air free conditions or not, are presented.

In Swedish practice, there is a long tradition of evaluating undrained shear strength from fall-cone tests and field vane tests. During the last 20 years cone penetration tests have also become widely used. However, the results from all these test methods have to be evaluated using empirical factors. The factors generally used for Swedish clays are related to liquid limit and overconsolidation, but they are not applicable to all types of fine-grained soils and can often be improved by local calibration for the particular type of soil in the area of current interest. For this calibration, the results of direct simple shear tests and/or triaxial tests in the laboratory are normally used. This paper presents an evaluation for Swedish fine-grained sulphide soils, for which a general correction factor of 0.65 for field vane tests and fall-cone tests, a cone factor Nkt of 20.2 for cone penetration tests and a relation cu,DSS/(σ′cOCR−0.2) of 0.28 have been found. No correlations were found between these empirical factors and the clay content, liquid limit or organic content, but a relationship was found between the overconsolidation ratio and both the cone penetration test and the field vane test. The sulphide soils in question are found in northern Sweden along the coast of the Gulf of Bothnia. They aremostly classified as organic silt or organic clay,which is normally silty.